Benzocaine-induced Methemoglobinemia

Asymptomatic benzocaine spray-induced methaemoglobinaemia in preoperative sedation for oesophagogastroduodenoscopy

Methaemoglobinaemia is defined as elevated methaemoglobin in the blood which is characterised by conversion of some of the reduced ferrous iron elements [Fe2+] to the oxidised ferric [Fe3+] form which does not have capacity to bind and transport oxygen resulting in functional anaemia. Causes can be genetic mutations or acquired by medications such as dapsone, nitrates or benzocaine. Benzocaine is currently being used as a topical anaesthetic agent before certain procedures. We report a case of benzocaine spray-induced methaemoglobinaemia in a patient who underwent oesophagogastroduodenoscopy for evaluation of upper gastrointestinal bleeding.

A Case of Congenital Methemoglobinemia: Rare but Real

Methemoglobin (MetHb) is a form of hemoglobin in which iron in Hb is in an oxidized form (ferric) instead of ferrous, making it difficult to bind with oxygen. Usually, MetHb is present in small quantities (<1%) in humans, but once MetHb increases beyond 3%, the condition is known as methemoglobinemia. It can be further classified into hereditary and acquired. Hereditary forms are a rare cause of hypoxia and cyanosis. Only a few cases have been reported worldwide. Here, we present a case of a 33-year-old female with congenital methemoglobinemia who remains relatively healthy in spite of her underlying condition. This case report focuses on knowledge sharing and practical aspects of managing patients with congenital methemoglobinemia.

A Rare Culprit of Methemoglobinemia

Methemoglobinemia is a rare cause of hypoxia and can be a diagnostic challenge early in the disease course. The incidence of medication-induced methemoglobinemia is more common than congenital-related methemoglobinemia. The most common cause of methemoglobinemia is exposure to household detergents, illicit drugs, or medications with nitrate or sulfonamide chemical groups. The 2 main medications accounting for up to 45% of medication-induced cases are dapsone and benzocaine. We report a case of hypoxia and diarrhea with an arterial blood gas (ABG) showing methemoglobinemia at 26%. Infectious and autoimmune workup were negative. Methemoglobinemia level returned to normal level within 2 weeks of hydrochlorothiazide discontinuation, suggesting medication-induced methemoglobinemia at appropriate hypertension dosage. In this case, there was an acute rise in methemoglobin levels following initiation of an hydrochlorothiazide-losartan combination, which improved following the discontinuation of hydrochlorothiazide. Extensive workup ruled out cytochrome b5 reductase (Cb5R) and Glucose-6-phosphate dehydrogenase (G6PD) deficiency, which raised the suspicion of hydrochlorothiazide-induced methemoglobinemia, as it is part of the sulfa drug family.

Wide-awake Local Anesthesia with No Tourniquet: An Updated Review

The wide-awake local anesthesia with no tourniquet (WALANT) technique has become popularized for various hand/upper extremity procedures. Before surgery, patients receive local anesthetic, consisting of lidocaine with epinephrine, and remain awake for the entire procedure. The purpose of this review was to investigate the advantages, diverse application, outcomes, cost benefits, use in challenging environments, patient considerations, and contraindications associated with WALANT.

METHODS

A comprehensive review of the literature on the WALANT technique was conducted. Search terms included: WALANT, wide-awake surgery, no tourniquet, local anesthesia, hand, wrist, cost, and safety.

RESULTS

The WALANT technique has proven to be successful for common procedures such as flexor tendon repair, tendon transfer, trigger finger releases, Depuytren disease, and simple bony procedures. Recently, the use of WALANT has expanded to more extensive soft-tissue repair, fracture management, and bony manipulation. Advantages include negating preoperative evaluation and testing for anesthesia clearance, eliminating risk of monitored anesthesia care, removal of anesthesia providers and ancillary staff, significant cost savings, and less waste produced. Intraoperative evaluations can be performed through active patient participation, and postoperative recovery and monitoring time are reduced. WALANT is associated with high patient satisfaction rates and low infection rates.

CONCLUSIONS

The WALANT technique has proven to be valuable to both patients and providers, optimizing patient satisfaction and providing substantial healthcare savings. As its application continues to grow, current literature suggests positive outcomes.

Prilocaine-Induced Methemoglobinemia

Local anesthetics are used to anesthetize surface areas in several procedures. The history of anesthesia exposure has been established as an important factor for correct diagnosis. When they are used excessively, some systemic side effects such as methemoglobinemia, respiratory failure, cardiovascular arrhythmias, or neurological manifestations may occur. Methemoglobinemia which usually presents with nonspecific symptoms is a serious entity. It is a rare but severe side effect of anesthetics. We herein present a case of methemoglobinemia due to local anesthesia with prilocaine.

Benzocaine: Review on a Drug with Unfold Potential

Benzocaine is well-known for its role as an anesthetic agent and largely used in oral ulcers, ear pain and dental complications. Along with lidocaine and other local anesthetics, benzocaine has marked it as an anesthetic agent in surgical procedures and as Na+ channels blocker, as well. Analogues of benzocaine have been found to possess biological potentials including antibacterial, antifungal and anti-cancer. Some derivatives were found to have conspicuous action against tuberculosis. The current review focuses to explore the century-long potential of the molecule and its analogs that have appeared in the literature. Furthermore, highlighting the biological potential of benzocaine and its analogues shall open-up new dimensions of future research to design more potent analogues.

Headache and Methemoglobinemia

AIM

This basic review is intended to summarize the current knowledge of methemoglobinemia as an important cause of secondary headache with the hope of generating a growing interest in studying this phenomenon.

BACKGROUND

We describe the pathological underpinnings of headaches generated by hypoxia. Possible mechanisms include cerebral vasodilation-associated stretching of the vessel nociceptors, sensitization of perivascular nociceptors mediated by nitric oxide, cerebral calcitonin gene-related peptide, activation of the cyclic adenosine monophosphate pathway, cortical spreading depression, disruption of the blood-brain barrier, and neurogenic inflammation. We review the clinical features, pathophysiology, and management of methemoglobinemia. We conducted a literature review of reports of symptomatic methemoglobinemia with headache. In addition, we describe a case report of a patient who presented with an acute onset of severe holocranial headache associated with rapidly progressive perioral paresthesia, cyanosis in lips and hands, nausea, and mild dyspnea on exertion. These features can be misinterpreted as an acute attack of migraine with pain-related hyperventilation syndrome and anxiety leading to clinically detrimental delay in the management of the progressive hypoxia. Her symptoms resolved following treatment with methylene blue. The complex relationship of migraine and hypoxia-related headaches is also reviewed. We propose that methemoglobinemia-associated headaches are possibly generated by stretching of the nociceptor nerve endings during cerebral vasodilation and hypoxia-mediated oxidative stress.

CONCLUSIONS

The case highlights the need to broaden the formulated differential diagnosis of an acute onset severe holocranial headache and pay careful attention to other signs and symptoms that may provide hints on potential mechanism(s) for secondary headaches. We provide justification for the need to incorporate "Headache attributed to Methemoglobinemia" as a subtype under the section "Headache attributed to hypoxia and/or hypercapnia" of the International Classification of Headache Disorders to support clinical decision making.

General Anesthesia in a Glucose-6-Phosphate Dehydrogenase Deficiency Child: A Case Report

We performed general anesthesia on a 3-year-old boy with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Patients with G6PD deficiency exhibit jaundice and anemia due to hemolysis caused by a lack of the G6PD enzyme. To maintain anesthesia, we used propofol and remifentanil, which may prevent hemolytic attacks by exerting an antioxidant effect. In addition, because the patient was in a high-risk group for the development of methemoglobinemia, we used mepivacaine as a local anesthetic. We liaised with the patient's attending physician to make sufficient arrangements, such as securing an emergency transfer on the day of anesthesia. The patient did not develop hemolytic attacks during or after the procedure, and he progressed well without problems.

Benzocaine-Induced Methemoglobinemia in a Postoperative Bariatric Patient following Esophagogastroduodenoscopy

Methemoglobinemia is a rare complication in clinical practice. It is most commonly seen in patients undergoing endoscopic procedures, including EGDs, laryngoscopies, bronchoscopies, and nasogastric tube insertions. This is thought to be a disease seen almost exclusively in patients with genetic predispositions to develop it; the increasing use of topical anesthetics during procedures has made methemoglobinemia a disease entity that every clinical provider should be able to recognize and treat. Clinically, patients become cyanotic with mild oxygen derangements on pulse oximetry, in the range of 84 to 90%. Paradoxically, these patients demonstrate normal to supranormal oxygen levels in the blood on blood gas analysis. We report a case of 34-year-old female postoperative Roux-en-Y gastric bypass patient who developed hypoxia and cyanosis after a routine EGD procedure to relieve a food impaction. Differentials of aspiration and pulmonary embolism were plausible; stat blood gas analysis clinched the diagnosis and managed with intravenous methylene blue.

An evaluation of 10 percent and 20 percent benzocaine gels in patients with acute toothaches: efficacy, tolerability and compliance with label dose administration directions

BACKGROUND

The authors evaluated the efficacy and tolerability of 10 percent and 20 percent benzocaine gels compared with those of a vehicle (placebo) gel for the temporary relief of toothache pain. They also assessed the compliance with the label dose administration directions on the part of participants with toothache pain.

METHODS

Under double-masked conditions, 576 participants self-applied study gel to an open tooth cavity and surrounding oral tissues. Participants evaluated their pain intensity and pain relief for 120 minutes. The authors determined the amount of gel the participants applied.

RESULTS

The responders' rates (the primary efficacy parameter), defined as the percentage of participants who had an improvement in pain intensity as exhibited by a pain score reduction of at least one unit on the dental pain scale from baseline for two consecutive assessments any time between the five- and 20-minute points, were 87.3 percent, 80.7 percent and 70.4 percent, respectively, for 20 percent benzocaine gel, 10 percent benzocaine gel and vehicle gel. Both benzocaine gels were significantly (P ≤ .05) better than vehicle gel; the 20 percent benzocaine gel also was significantly (P ≤ .05) better than the 10 percent benzocaine gel. The mean amount of gel applied was 235.6 milligrams, with 88.2 percent of participants applying 400 mg or less.

CONCLUSIONS

Both 10 percent and 20 percent benzocaine gels were more efficacious than the vehicle gel, and the 20 percent benzocaine gel was more efficacious than the 10 percent benzocaine gel. All treatments were well tolerated by participants. Practical Implications. Patients can use 10 percent and 20 percent benzocaine gels to temporarily treat toothache pain safely.

Evaluation and management of acquired methemoglobinemia associated with topical benzocaine use

Benzocaine is a widely used topical oropharyngeal anesthetic and has been reported to cause methemoglobinemia. We discuss benzocaine-induced methemoglobinemia and review the causes, presentation, and management of this serious complication. Treatment with methylene blue will result in reversal of methemoglobinemia and clinical recovery in most cases but needs to be used at appropriate doses in carefully selected individuals. Physicians who perform procedures involving the application of benzocaine for topical anesthesia need to rapidly identify and treat methemoglobinemia to avoid significant associated morbidity and mortality.

Liposomal-benzocaine gel formulation: correlation between in vitro assays and in vivo topical anesthesia in volunteers

The aim of the present study was to characterize a liposome-based benzocaine (BZC) formulation designed for topical use on the oral mucosa and to evaluate its in vitro retention and permeation using the Franz-type diffusion cells through pig esophagus mucosa. To predict the effectiveness of new designed formulations during preclinical studies, a correlation between in vitro assays and in vivo efficacy was performed. Liposomal BZC was characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and morphology. Liposomal BZC (BL10) was incorporated into gel formulation and its performances were compared to plain BZC gel (B10) and the commercially available BZC gel (B20). BL10 and B10 presented higher flux and retention on pig esophagus mucosa with a shorter lag time, when compared to B20. BZC flux was strongly correlated with in vivo anesthetic efficacy, but not with topical anesthesia duration. The retention studies did not correlate with any of the in vivo efficacy parameters. Thus, in vitro permeation study can be useful to predict anesthetic efficacy during preclinical tests, because a correlation between flux and anesthetic efficacy was observed. Therefore, in vitro assays, followed by in vivo efficacy, are necessary to confirm anesthetic performance.

Methaemoglobinaemia associated with the use of cocaine and volatile nitrites as recreational drugs: a review

Methaemoglobinaemia can cause significant tissue hypoxia, leading to severe, potentially life-threatening clinical features and/or death. Over recent years there have been increasing reports of methaemoglobinaemia related to recreational drug use. There have been 25 articles describing methaemoglobinaemia related to recreational use of volatile nitrites (poppers) and more recently, four reports of methaemoglobinaemia in association with recreational cocaine use. In this article we discuss the mechanisms by which methaemoglobinaemia occurs in relation to the use of both volatile nitrites and cocaine, and summarize the published cases of recreational drug-related methaemoglobinaemia. The volatile nitrites can cause methaemoglobinaemia directly through their activity as oxidizing agents. However, with cocaine, methaemoglobinaemia is related to adulterants such as local anaesthetics or phenacetin, rather than to the cocaine itself. Clinicians managing patients with acute recreational drug toxicity should be aware of the potential for methaemoglobinaemia in these patients, particularly in patients with cyanosis or unexplained low oxygen saturations on pulse oximetry, and ensure that appropriate and timely management is provided, including, where appropriate, the use of methylthioninium chloride (methylene blue).

Glucose-6-phosphate dehydrogenase deficiency and cardiac surgery

Cardiac surgery involving cardiopulmonary bypass (CPB) in its conventional form involves many processes leading to free radical production, such as perioperative ischemia, reperfusion, circulation of whole body blood through the CPB circuit, hypothermia and acidosis. The red blood cells of a glucose-6-phosphate dehydrogenase (G6PD)-deficient person are unable to scavenge these free radicals, resulting in haemolysis. Here, we describe the successful anaesthetic management of two G6PD-deficient children who underwent cardiac surgery, on and off CPB, without any obvious haemolytic reaction, followed by a discussion of the disorder, with specific consideration of perioperative management of such cases.

Liposomal encapsulation improves the duration of soft tissue anesthesia but does not induce pulpal anesthesia

STUDY OBJECTIVE

To compare the topical and the pulpal anesthesia efficacy of liposomal and plain benzocaine formulations.

DESIGN

Double-blinded, randomized crossover study.

SETTING

University ambulatory dental center.

PATIENTS

30 ASA physical status I volunteers.

INTERVENTIONS

Volunteers received, in three different sessions, topical application of liposome-encapsulated 10% benzocaine (LB10), 10% benzocaine gel (B10), and 20% benzocaine gel (B20) in the right maxillary canine mucobuccal fold.

MEASUREMENTS

Pain associated with the needle insertion was rated by visual analog scale (VAS) and the duration of topical anesthesia was recorded. Pulpal anesthesia was evaluated using an electric pulp tester.

MAIN RESULTS

VAS values (median, 1st - 3rd quartiles) were 17 cm (11 - 25), 14 cm (3 - 22), and 21 cm (9 - 21) for B10, LB10, and B20, respectively. No differences were noted among the groups (Friedman test; P = 0.58). Soft tissue anesthesia was also not different. The LB10 [10 (8 - 12) min] showed longer soft tissue anesthesia (Friedman test; P < 0.01) than the other agents [B10 = 8 (5 - 10) min, and B20 = 7 (6 - 9) min]. None of the topical benzocaine formulations tested induced pulpal anesthesia.

CONCLUSIONS

The encapsulation of benzocaine into liposome increased the duration of soft tissue anesthesia. However, it did not induce pulpal anesthesia.

Perioperative management of the glucose-6-phosphate dehydrogenase deficient patient: a review of literature

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymatic disorder of red blood cells in humans. It is estimated that about 400 million people are affected by this deficiency. The G6PD enzyme catalyzes the first step in the pentose phosphate pathway, leading to antioxidants that protect cells against oxidative damage. A G6PD-deficient patient, therefore, lacks the ability to protect red blood cells against oxidative stresses from certain drugs, metabolic conditions, infections, and ingestion of fava beans. The following is a literature review, including disease background, pathophysiology, and clinical implications, to help guide the clinician in management of the G6PD-deficient patient. A literature search was conducted in the following databases: PubMed, The Cochrane Library, Web of Science, OMIM, and Google; this was supplemented by a search for selected authors. Keywords used were glucose-6-phosphate dehydrogenase (G6PD) deficiency, anesthesia, analgesia, anxiolysis, management, favism, hemolytic anemia, benzodiazepines, codeine, codeine derivatives, ketamine, barbiturates, propofol, opioids, fentanyl, and inhalation anesthetics. Based on titles and abstracts, 23 papers and 1 website were identified. The highest prevalence of G6PD is reported in Africa, southern Europe, the Middle East, Southeast Asia, and the central and southern Pacific islands; however, G6PD deficiency has now migrated to become a worldwide disease. Numerous drugs, infections, and metabolic conditions have been shown to cause acute hemolysis of red blood cells in the G6PD-deficient patient, with the rare need for blood transfusion. Benzodiazepines, codeine/codeine derivatives, propofol, fentanyl, and ketamine were not found to cause hemolytic crises in the G6PD-deficient patient. The most effective management strategy is to prevent hemolysis by avoiding oxidative stressors. Thus, management for pain and anxiety should include medications that are safe and have not been shown to cause hemolytic crises, such as benzodiazepines, codeine/codeine derviatives, propofol, fentanyl, and ketamine. The authors of this article make 5 particular recommendations: (1) Anyone suspected of G6PD deficiency should be screened; (2) exposure to oxidative stressors in these individuals should be avoided; (3) these patients should be informed of risks along with signs and symptoms of an acute hemolytic crisis; (4) the clinician should be able to identify both laboratory and clinical signs of hemolysis; and finally, (5) if an acute hemolytic crisis is identified, the patient should be admitted for close observation and care.

Topical benzocaine-induced methemoglobinemia in the pediatric population

Topical benzocaine is an anesthetic agent that is often used before procedures and clinical tests, such as esophagoscopy, bronchoscopy, and endotracheal intubation. However, a potential deadly condition known as methemoglobinemia can occur with this agent. It causes the oxidation of hemoglobin to methemoglobinemia to occur more rapidly than the reduction of methemoglobin back to hemoglobin. Certain congenital and clinical conditions that affect oxygen delivery can increase the patient's risk of having methemoglobinemia develop with the use of benzocaine. Topical benzocaine-induced methemoglobinemia can occur in the pediatric population. Prompt management with intravenous methylene blue should be initiated for reversal.

Benzocaine and lidocaine induced methemoglobinemia after bronchoscopy: a case report

Introduction

Methemoglobinemia is a rare cause of hypoxemia, characterized by abnormal levels of oxidized hemoglobin that cannot bind to and transport oxygen.

Case presentation

A 62-year-old male underwent bronchoscopy where lidocaine oral solution and Hurricaine spray (20% benzocaine) were used. He developed central cyanosis and his oxygen saturation was 85% via pulse oximetry. An arterial blood gas revealed pH 7.45, P_CO2 42, P_O2 282, oxygen saturation 85%. Co-oximetry performed revealed a methemoglobin level of 17.5% (normal 0.6–2.5%). The patient was continued on 15 L/minute nonrebreathing face mask and subsequent oxygen saturation improved to 92% within two hours. With hemodynamic stability and improved SpO₂, treatment with methylene blue was withheld.

Conclusion

Methemoglobinemia is a potentially lethal condition after exposure to routinely used drugs. Physicians should be aware of this complication for early diagnosis and treatment.

Skin surgery in children: local anaesthesia and sedation techniques

In the past, procedural pain control in young children was undertreated as it was incorrectly alleged that their neuronal pain pathways were undeveloped. However, it is now recognised that even neonates are able to experience pain. Moreover, intensely painful physical experiences in childhood can have persisting physiological and psychological consequences. Therefore, the management of acute pain is essential. In this paper, the authors provide an in-depth discussion regarding the anaesthetic options for paediatric patients undergoing dermatological surgery.